uBO has documentation to so called Blocking modes. I myself go even a step further and disable Domain and Inline scripts by default, basically whitelist mode instead of blacklist (about 1/3 of pages work better that way, if you only want to read the fucking text).
Are there matching filter lists who enable scripts/content for respective domains, at least for medium and hard mode? some Webapps like microsofts are a pain to deal with manually, with all their redirects.
What modern features do you mean?
The only problem I’ve noticed since uMatrix stopped getting updates is that I now have to Ctrl+Shift+R instead of just Ctrl+R to get scripts to work after adjusting a site’s permissions.
Some webextension features & security stuff i believe? Someone once explained it in length here, a few months ago.